1 #ifndef LIB2GEOM_UTILS_HEADER
2 #define LIB2GEOM_UTILS_HEADER
4 /** Various utility functions.
5 *
6 * Copyright 2007 Johan Engelen <goejendaagh@zonnet.nl>
7 * Copyright 2006 Michael G. Sloan <mgsloan@gmail.com>
8 *
9 * This library is free software; you can redistribute it and/or
10 * modify it either under the terms of the GNU Lesser General Public
11 * License version 2.1 as published by the Free Software Foundation
12 * (the "LGPL") or, at your option, under the terms of the Mozilla
13 * Public License Version 1.1 (the "MPL"). If you do not alter this
14 * notice, a recipient may use your version of this file under either
15 * the MPL or the LGPL.
16 *
17 * You should have received a copy of the LGPL along with this library
18 * in the file COPYING-LGPL-2.1; if not, write to the Free Software
19 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
20 * You should have received a copy of the MPL along with this library
21 * in the file COPYING-MPL-1.1
22 *
23 * The contents of this file are subject to the Mozilla Public License
24 * Version 1.1 (the "License"); you may not use this file except in
25 * compliance with the License. You may obtain a copy of the License at
26 * http://www.mozilla.org/MPL/
27 *
28 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
29 * OF ANY KIND, either express or implied. See the LGPL or the MPL for
30 * the specific language governing rights and limitations.
31 *
32 */
34 #include <cmath>
36 namespace Geom {
38 // proper logical xor
39 inline bool logical_xor (bool a, bool b) { return (a || b) && !(a && b); }
41 /** Sign function - indicates the sign of a numeric type. -1 indicates negative, 1 indicates
42 * positive, and 0 indicates, well, 0. Mathsy people will know this is basically the derivative
43 * of abs, except for the fact that it is defined on 0.
44 */
45 template <class T> inline int sgn(const T& x) {return (x < 0 ? -1 : (x > 0 ? 1 : 0) );}
47 template <class T> inline T sqr(const T& x) {return x * x;}
48 template <class T> inline T cube(const T& x) {return x * x * x;}
50 /** Between function - returns true if a number x is within a range. The values delimiting the
51 * range and the number must have the same type.
52 */
53 template <class T> inline const T& between (const T& min, const T& max, const T& x)
54 { return min < x && max > x; }
56 /** Returns x rounded to the nearest integer. It is unspecified what happens
57 * if x is half way between two integers: we may in future use rint/round
58 * on platforms that have them.
59 */
60 inline double round(double const x) { return std::floor(x + .5); }
62 /** Returns x rounded to the nearest \a places decimal places.
64 Implemented in terms of round, i.e. we make no guarantees as to what happens if x is
65 half way between two rounded numbers.
67 Note: places is the number of decimal places without using scientific (e) notation, not the
68 number of significant figures. This function may not be suitable for values of x whose
69 magnitude is so far from 1 that one would want to use scientific (e) notation.
71 places may be negative: e.g. places = -2 means rounding to a multiple of .01
72 **/
73 inline double decimal_round(double const x, int const places) {
74 //TODO: possibly implement with modulus instead?
75 double const multiplier = std::pow(10.0, places);
76 return round( x * multiplier ) / multiplier;
77 }
79 }
81 #endif
83 /*
84 Local Variables:
85 mode:c++
86 c-file-style:"stroustrup"
87 c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
88 indent-tabs-mode:nil
89 fill-column:99
90 End:
91 */
92 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=99 :